Some state-of-the-art intelligent video surveillance (IVS) system can perform content analysis on frames generated by surveillance cameras. Based on user-defined rules or policies, IVS systems can automatically detect potential threats by detecting, tracking and analyzing the targets in the scene. One significant constraint of the system is that the targets have to be isolated in the camera views. Existing IVS systems have great difficulty in tracking individual targets in a crowd situation, mainly due to target occlusions. For the same reason, the types of targets or the behaviors of the targets that a conventional IVS system can distinguish are also limited.
In many situations, security needs demand much greater capabilities from an IVS. One example is the detection of shoplifting. Theft from stores, including employee and vendor theft, costs retailers many billions of dollars per year. Independent retail studies have estimated that theft from retail stores costs the American public between 20 and 30 billion dollars per year. Depending on the type of retail store, retail inventory shrinkage ranges from 0.5%-6% of gross sales, with the average falling around 1.75%. Whole retail store chains have gone out of business due to their inability to control retail theft losses. Although most stores have video surveillance cameras installed, most of them just serve as forensic tape providers. Intelligent real-time theft detection capability is highly desired but is not available.
Certain suspicious activities by customers in retail stores could be indicators of potential theft. Examples of these include when a person takes and replaces a single item from a store shelf multiple times, and when a person takes more than the typical number of items from a shelf. Shoplifting rates can be greatly reduced if an IVS system can detect such suspicious activities and alert store management in real time.
Another exemplary scenario in which multi-grabbing may occur is in a gaming milieu. A casino, for example, may be concerned about monitoring when gaming participants reach onto gaming tables. Multi-grabbing in this scenario may reflect cheating and/or stealing. In particular, most casinos have rules applying to various gaming tables that require that no player reach beyond a certain threshold, into the domain of the dealer. This is to prevent players from reaching in and grabbing a stack of chips or cash. An algorithm to detect the motion of a player (that is, hand and arm) crossing this (generally invisible) threshold in a particular direction and then returning, while ignoring the opposite motion (e.g., by the dealer) would thus be useful to the casino owner.